The invention relates to improvements in machines or groups of machines (hereinafter called machining centers) for removal of material from large or medium-sized workpieces.
Multi-stage treatment of medium-sized or large workpieces is normally carried out in a series of discrete machines. For example, successive workpieces must be transported to and from discrete milling, drilling, turning, grinding, shaving and other machines in order to perform the respective treatments in a particular sequence. A drawback of such mode of treatment of workpieces is that each treatment requires a very long interval of time since a substantial part of the overall treatment involves the transport of untreated, partially treated and finished workpieces to and from each of a long series of discrete machine tools. Typical examples of workpieces which require a multi-stage treatment (normally including milling, drilling or boring, shaving, grinding and/or other operations) are machine tool frames, blocks for diesel engines which are used in watercraft, and other bulky parts.
A group of machines for treating five sides of workpieces is described by R. Binder and H. Hammer on pages 195-198 in No. 4 of the 1983 edition of German-language publication entitled "Werkstatt-Technik - wt - Zeitschrift fur industrielle Fertigung". A drawback of such machines is that it still takes a relatively long interval of time to complete the treatment of a medium-sized or large workpiece.